The present invention relates to a system and method for controlling the ignition timing of an internal combustion engine such as an automotive engine.
A learning control system for correcting the ignition timing has been proposed. The control system is adapted to advance the ignition timing so as to produce a maximum torque as long as the level of engine knocking does not exceed a tolerable level. The ignition timing stored in a RAM is corrected by a small correcting quantity (quantity of correction) and converged to a desired value little by little. The correcting quantity for the ignition timing at every updating operation is gradually reduced as the number of the learning increases, that is as the ignition timing approaches the desired value.
On the other hand, when the engine is accelerated, the ignition timing is reduced in order to increase the power of the engine. In a conventional ignition timing learning control system, a single program is provided for correcting the ignition timing including the ignition timing for the acceleration. Since the program is provided for correcting the timing at steady state of engine operation, the program comprises a plurality of steps in order to finely correct the timing. Accordingly, it takes a long time to advance the timing at the acceleration. As a result, the ignition can not be sufficiently advanced to meet the requirement of the acceleration.